The need for biofuels as an alternative and a low-carbon energy source to combat climate change, meet up with growing energy needs, and ensure sustainable fuel supply has become more pronounced now than ever before. The pyrolysis of softwood Kraft lignin, an irreversible process of chemically decomposing this aromatic biopolymer at elevated temperatures in the absence of oxygen, shows great promise for converting lignin and other wood components into biochemicals, biomaterials, and biofuels. Pyrolysis processes are differentiated by the temperatures and vapor residence times of the lignin biomass. For optimum liquid biofuel production, moderate temperatures and shorter vapor residence times are generally required. Any unconventional approaches that may improve biofuel yields and product selectivity are highly desirable. A better alternative to above conventional methods of pyrolysis can be infrared pellet ablation technique. The low power of IR CO2 laser energy (a few watts), and a fast flow of the carrier gas N2 through the reactor, in which a pellet from Kraft lignin/KBr is located, is desirable to rapidly desorb products from the pellet surface, minimizing unwanted secondary reactions and interactions of released products with the hot surface of pellets. Apart from the relatively low cost of using CO2 lasers, the CO2 laser ablation process offers faster gas absorption rates, photochemical heat transfer, and high wavelength bands (9.4 – 10.6 micrometers) thus making it suitable for Kraft lignin, as compared to UV lasers with lower wavelengths. The ablation of high content of Kraft lignin pellets (50% and up) reveals distribution of products that was similar to the results obtained for the conventional fast pyrolysis of Kraft lignin without additives. However, the products yield dropped un-predictably on reducing Kraft lignin percentage in the pellets. For instance, guaiacol and vanillin were the major products from the ablation of pellets with lower content of Kraft lignin of less than 20% by mass.

Distribution of products from Kraft lignin ablation with IR CO2 laser

255th National Meeting (2018)

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